1. Field of the Invention
The present invention relates to a high-voltage power supply apparatus used for an image forming apparatus or the like, and to an image forming apparatus including the high-voltage power supply apparatus.
2. Description of the Related Art
In the related art, there is known an electrophotographic image forming apparatus as an image forming apparatus such as a copying machine, a printer, or a fax machine. In the electrophotographic image forming apparatus, a high voltage is applied to a charging member for uniformly charging an image bearing member and to a developing member for developing a latent image formed on the image bearing member by using toner as developer. Further, in the electrophotographic image forming apparatus, a transfer member for transferring a toner image formed on the image bearing member onto a recording material is also applied with a high voltage so as to form an image. A high voltage used for forming an image is generated by a high-voltage power supply apparatus, and a technology for applying a high voltage to each member is described in, for example, Japanese Patent Application Laid-Open No. 2012-120439.
FIG. 1 is a circuit diagram of a high-voltage power supply apparatus described in Japanese Patent Application Laid-Open No. 2012-120439. In the high-voltage power supply apparatus illustrated in FIG. 1, a drive signal having a fixed switching frequency and a variable pulse duty is input to a switching element Q101 for driving a voltage resonance circuit so as to control an output voltage Vout. Note that, detailed description of FIG. 1 is given in a first embodiment of the present invention. In FIG. 1, when a load 110 is short-circuited, a controller 101 sets the duty for driving the switching element Q101 to 100% in order to supply larger current to the load 110. In this way, larger current is supplied to the load 110, but there is a problem in that a circuit component may be broken down because current larger than a rated current value flows through an inductor L100 or the switching element Q101. In addition, for example, by disposing a current detection circuit for detecting current flowing through the inductor L100 or the switching element Q101 so as to stop to drive the switching element when overcurrent is detected, it is possible to prevent the circuit component from being broken down. However, when the circuit is added, a circuit scale is increased, and hence there occur problems in that downsizing of the high-voltage power supply apparatus is affected, and cost is increased due to the addition of the circuit.